Multiple complex machines and instruments are needed for monitoring and conducting various industrial activities in adverse environments. For example, deep-sea oil drilling or a well-drilling through a petroleum reservoir requires multiple instruments to monitor the progress, carefully balance the physical parameters, or determine the status of the surroundings. In the case of a petroleum reservoir, reservoir parameters such as pressure, temperature, fluid flow rate, and the like provide useful information about the status of the reservoir and the development of the well.
Sensors that are responsive to these parameters are being used in the industry to obtain the status updates and monitor the progress of underwater operations. The monitors are suitably positioned within the well such that the information regarding the reservoir parameters can be obtained. The sensor takes the measurements and transmits the measurements to a data recorder that is coupled to the reservoir or to a work station (e.g., computer) or a control module on the surface.
Operation of instruments such as sensors requires electrical and data connections between these machines. Often, these connections must be made within the adverse environment, such as within the wellbore. Such connections may require “wet-mateable” electrical or data connectors.
The wet-mateable electrical connection must be reliable to ensure the proper monitoring of the reservoir parameters. For example, in deep sea well-drilling, the wellhead assembly and the valve system are installed separately. Thus, a wet-mateable connector is required to make a connection at the wellhead. For such an operation, the electrical connection must be durable because the wellhead assembly and the valve system are permanently installed on the sea floor. Additionally, since a high voltage is often required for operation of downhole equipment and sensors, the electrical connection should be able to insulate high voltage after being pressure sealed from conductive seawater and/or production of well-fluid.
A challenge in making wet-mateable electrical connections is the ability to protect the electrical contacts from influx of seawater and/or well-fluid. Currently, this challenge has been addressed in many ways. A general premise of current protection methods is the insulation of the electrical connects from water or fluids. For example, U.S. Pat. No. 4,795,359 to Alcock, et al. is directed to a wet-mateable electrical connector where the male connector and the female connector are enclosed within closed chambers that contain electrically insulating media, such as grease or oil. The electrically insulating media provides a protected area around the connection between contact pin and the contact socket within the female connector body.
U.S. Pat. No. 4,174,875 to Wilson, et al. discloses an electrical insulation of male and female connectors of a wet-mateable electrical connection using a rigid dielectric material disposed between them. U.S. Pat. No. 5,772,457 to Cairns discloses a plurality of electrically-conductive sockets where each socket assembly is pressure compensated to the ambient external pressure by means of one or more of resilient bladders filled with dielectric fluid. Several other wet-mateable electrical connections are known in the art and disclose similar techniques for insulating the electrical contacts. See for example, U.S. Pat. Nos. 4,039,242, 5,645,442, and 4,192,569.
In addition to bladders and enclosed chambers containing insulating media, the prior wet-mateable electrical connection assemblies also contain several mechanical components such as pistons, elastomeric sealings and the like. The purpose of these components is to prevent the influx of seawater or fluid into the electrical contact area. However, these bladders, chambers, mechanical components and elastomeric sealings cannot withstand the long term exposure to high pressure and temperature resulting in seawater or moisture penetration into the electrical contacts. As a result, the electrical contacts can develop short circuits, or worse, can fail completely. Once the moisture or fluids come into contact with the electrical contacts, the prior devices are not built to remedy such a failure. The current industry practice of using oil-bladder designs is complicated, causes high mating forces, results in bulky and heavy connectors which are difficult to maneuver, degrades in performance after exposure to temperature extremes, requires pressure compensation for the oil bladders, and limits the number of mate-demate cycles before maintenance is required. Current designs also operate over a narrow range of mating rates.